Electrical condenser



July 26, 1932; B. J. BUTLER ELECTRICAL CONDENSER Filed Dec. 6. 1927 1| III [All www Patented July 26, 1932 UNITED sTATEs PATENr carica BENJAMIN J. BUTLER, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR, MESNE AS- I SIGNMENTS, TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW" YORK ELECTRICAL CONDENSEE Application filed December 6, 1927.. `Seria1 ANo. 238,076.

' This invention relates to electrical condensers and,more particularly, to a new and improved bushing for insulating a high potential terminal thereof from the casing.

The invention provides a high 'potential bushing which may be readily inserted 1n the condenser casing and secured therein and is adapted to positively separate the high potential stud from the casing, both electrically and mechanically. A corona shield is secured lto the stud for distributing the electrostatic stress and for protecting the bushing from mechanical injury.

The invention also consists in certain new and original features of construction and l combinations of parts hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its organization may be better understood by referringv to the following description taken in con# nection with the accompanying drawing forming a part thereof, in which I Fig. 1 is a central vertical section of the condenser fitted with the bushing in accordance with the present invention;

Fig. 2 is a detail view showing the method of assembling the condenser and bushing; and

Fig. 3 is a top plan view` of .the bushing.

Like reference characters denote like parts in the several figures pf the drawing. l

In the following description and in the claims parts will be identified by specific names for convenience, but they .are intended to be as generic in their application to similar parts as the art will permit.

Referring more particularly to the drawing, especially to Fig. l, the condenser and 'casing therefor are formed in the usual manner, comprising for example a pair of condenser stacks S separat-ed by mid-plate MP and clamped under pressure by means of screw clamps SC carried by casing C,

Casing C is open at the bottom to permit wthe parts to be readily assembled and is provided at the top with an opening through which the high potential stud HPS may pass. Said stud is threaded or otherwise secured to mid-plate MP and forms one terminal for the condenser, the other terminal being provided by casing C. Cover plate CP may close the bottom of the casing after the mechanism has been assembled and is secured by any suit,

able means.

The bushing PB, which may be formed of porcelain or other suitable refractory insulating material, comprises a substantially cylindrical and a ottom flange BF by means of which the bushing is secured in place. The bushing is recessed to permit free passage ofthe high potential stud HPS and is preferably entirely ,out of contact with said stud with the exception of the clamping means thereof, to be described. t The bushing is heldin the casing as by means of washer LW 2 which may be formed of lead or other soft material whereby injury is prevented, said washer being secured therethrough.

"rThe bushin may be clamped upon the high potential stud jury to the bushing, and washer LW 3 which may be formed of lead. Washer LW 1 may be held in contact with the top of bushin TB as by Spanner nut SN threaded upon the igh potential stud and washer LW 8 may be secured against the lower portion of said bushing in a recess formed therein as by means of nut N 3. Metal washer MW 3 may be inserted between nut N 3 and washer LW 3' ortion having a corrugated surface by metal ring MR and cap screws CS passingbetween the washerLW 1,4 preferably formed of leather to prevent inconnection may be secured to the hi h potential stud in any suitable manner as y means -of metal washers MW` l and MW 2 and creeping thereover.

In assembling the condenser temporary bar AF, as shown in Fi 2, may be secured to high potential stud HP as by nut N 2 and .utilized for holding the base flange BF of bushing PB. securely a' ainst'washer LW 2. After the condenser place and the casing filled with suitable insulating material, the temporary bar AF may be removed and the. corona shield CS ap plied. I

The above described bushing isV so constructed as to effectively insulate the high potential terminal of the condenser from the low otential casing and may be readily 'applie when the condenser is assembled. After the condenser is completed, the bushing is'v permanently held in place by the high pof tential stud. Washers of soft material, such as lead or leather, vaie employed to prevent the pressure used in clamping the bushing from damaging the same and to ermit a certain resilienc during use for ta ng up mechanical shocks and compensating for any expansion or contraction that may take place.

From Fig. l of the drawing the recess CO on the under side of the bushing'PB is a desirable feature because on coolin an insulating embedment generally shrin s. Where such contraction occurs an air space is left 'with the result that if this air space is in the Yhigh potential field it is not strong and resistant to creepage, breakdown etc. The particular shape of bushing PB enables any such shrinkage and air s ace to occur in the recessl CO on the under side of the bushing with# out serious damage because any such air' space is reinforced electrically by the downward extending fiange F. It will be seen this tion have been shown and described and are pointed out in the annexed claims,it will be flange F projects in the densest portion of thel field between the casing and high potential terminal for the purpose ofv keeping up the strength and insulation resistance between these high potential parts should it become weakened by shrinkage cracks or air spaces in the recess CO. Y

While certain novel features of the inveniinderstood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its operation may as been securely clamped in be made by those skilled in the art without departing from the s irit of the invention.

What is claime is: 1. The combination with a capacitor stack provided with clamping means therefor, of

a yrigidvterniinal stud secured intermediate the ends of said stack, a casing for said stack,

an insulatin bushing closing a portion of the outer wa l of said casing, said stud passing thru said bushing and having clearance between the stud and bushing whereby variation in clamping dangerous stresses on said stack transmits no stresses to said bushing, a d means'seali'ng each end of said clearance space between the bushing and said stud.

3. The combination with a capacitor stack provided with clamping means therefor, of a rigid terminal stud secured intermediate the ends of said stack, a casing for said stack, insulating material constituting at least a portion of the outer wall of said casing, said stud passing thru said insulating material and having clearance between the stud and insulating material whereby variation in clamping stresses on said stack transmits no stresses to said .insulating material, and

means sealing each end of said clearance spacebetween the insulating material and said stud, each/ of said sealin means compris-y 'mits no stresses to said insulating material,

said bushing being at least supported in part by said stack.

In testimony whereof I hereunto affix my signature.

. BENJ. J. BUTLER. 

